Our invention relates to switching networks generally and more particularly to an arrangement for tearing down existing paths in a progressively controlled multistage switching network.
Progressively controlled switching networks comprise a number of switching stages which combine both control and switching in each stage. Connection paths are set up and torn down by sending control signals to each network stage. The control signals indicate what action is to be taken by the network stage and, for a connection path setup, identify the required connection. For example, control signals are sent initially to a first stage to identify and establish a required connection path through that first stage. After the first stage connection path is established, control signals are sent through that first stage connection path to the second stage of the switching network which is connected by the first stage connection path. The control signals sent to the second stage of the switching network identify and command a required connection path through that second stage of the switching network. The progressive control continues through all stages of the switching network until the total required connection path is completed through the network.
After a connection path has been utilized and is no longer required, the individual connection paths through the stages of the switching network must be torn down or idled so that new connection paths can be set up for subsequent connection tasks. In prior art progressively controlled switching networks, existing connection paths are idled by sending tear down control signals to the control portions of all stages in the switching network via the existing connection path through the switching network. The transmission of the teardown control signals and the time required for the switching network to respond to the teardown control orders create a time delay before new connection paths through the switching network can be established.